Automatic ignition and control mechanism for gas burners



Aug. 18, 1953 c. M. MAYER ET AL NTROL MECHANISM FOR GAS BURNERS AUTOMATIC IGNITION AND CO 5 Sheets-Sheet 1 Filed June 29, 1950 Aug. 18, 11953 c. M. MAYER ET AL 2,649,152

AUTOMATIC IGNITION AND CONTROL MECHANISM FOR GAS BURNERS Filed June 29, 1950 5 Sheets-Sheet 2 INVENTOR$ (was. M. Ma er K dmue/ 71 Pal flg BY Aug. 18, 1953 c. M. MAYER ET AL AUTOMATIC IGNITION AND CONTROL MECHANISM FOR GAS BURNERS 5 Sheets-Sheet 3 Filed June 29, 1950 Aug. 18, 1953 AUTOMATIC IGNITION AND CONTROL MECHANISM FOR GAS BURNERS Filed June 29, 1950 c. M. MAYER ET AL 2,649,152

5 Sheets-Sheet 4 I77 1 ma: 93 '76 if F V L IN ENTORS Chas/Z Mayer y 96210100 I 6rd! Aug. 18, 1953 c. M. MAYER ET AL AUTOMATIC IGNITION AND CONTROL MECHANISM FOR GAS BURNERS 5 Sheets*Sheet 5 Filed June 29, 1950 INVENTORS Chas" M. Mayer BY 9 Samuel 7:671:5 A M Patented Aug. 18, 1953 UNITED STTES TENT OFFICE AUTOMATIC IGNITION AND CONTROL MECHANISM FOR GAS BURNERS Ohio Application June 29, 1950, Serial No. 171,190

13 Claims.

This invention relates to automatic ignition and control mechanisms for cooking range burners using gaseous fuel. It is especially adapted for controlling the operation of oven burners in cooking ranges, and may be used in conjunction with a time control mechanism or independently thereof, as desired. It is an improvement of the I control mechanism disclosed in our co-pending application Serial No. 86,932, filed April 12, 1949, now Patent No. 2,607,407.

The mechanism is designed for use with a main gaseous fuel oven burner which is adapted to be ignited by a gaseous fuel pilot burner which burns constantly while the oven burner is turned on. When the oven burner is turned off the pilot burner is extinguished. In most cooking ranges in use today it is immaterial whether or not the oven burner burns constantly while in use as long as the pilot burner associated therewith is ignited. The oven burner may be extinguished for some reason during use but it Will be promptly re-ignited by the pilot burner if fuel is supplied thereto. But if the pilot burner is extinguished for any reason while the oven burner is turned on a very dangerous situation sometimes arises. Let us assume that both the pilot burner and the oven burner are extinguished during use for some reason. Gas can then flow to the oven burner but since the pilot burner is extinguished the oven burner will not be reignited and unburned gas will accumulate in the oven which may violently explode when an attempt is made to re-ignite either the pilot burner or the oven burner. It has been found by eX- perience that both the pilot burner and the main burner are frequently extinguished during use. It has also been found that sometimes the pilot burner alone is extinguished during use. The momentary failure of the gas supply or the slamming of the oven door or various other conditions may produce these results.

In order to prevent an accumulation of unburned gas in an oven and thus eliminate danger of an explosion in the event the pilot burner is extinguished for any reason during use, we incorporate in our control mechanism means by which the supply of gas to both the main burner and the pilot burner is completely out off, independently of the main control valve, in the event the pilot burner is extinguished for any reason during use.

One form of our improved ignition and control mechanism, as shown in Figs. 1 to 3, includes a main gaseous fuel burner which is suitably 2 mounted in a cooking range oven, and is adapted to be ignited by a gaseous fuel pilot burner which burns constantly while the oven is in use. At other times the supply of fuel to both the main burner and the pilot burner is cut off by a manually operated main control valve which is interposed in a conduit between the gas supply manifold and the burners. When the main control valve is open gas will flow from the manifold through the main control valve and into an oven temperature control valve. After leaving the main control valve gas will also flow to the pilot burner through a small branch conduit which is connected to the main conduit between the main control valve and the oven temperature control valve. From the oven temperature control valve gas flows through the main conduit to the main or oven burner. In the main conduit between the oven temperature control valve and the oven burner we interpose a solenoid operated valve, and we interpose a similar valve in the branch conduit between the main conduit and the pilot burner. Both of these valves are normally closed and are adapted to be opened and held open by their respective solenoids when the solenoids are ed by the pilot burner.

energized. The energization of the solenoids is controlled by a pair of normally open switches which are adapted to be closed by a thermostatic element which is mounted in position to be heat- An electric resistance ignition element is mounted adjacent the pilot burner and the thermostatic element in position to heat the thermostatic element and to ignite the pilot burner after it has been energized. The energization of the electric resistance ignition element is controlled by a normally open manually operated master control switch and a normally closed switch which is adapted to be opened by the thermostatic element. The master control switch is operatively associated with the main control valve and is arranged to be closed by the opening of the main control valve and to be opened by the closing of the master control valve. The closing of the master control switch by the opening of the main control valve to sup: ply gas to the burner effects the energization of the electric resistance ignition element and the opening of the normally closed switch by the thermostatic element effects the de-energization of the electric resistance ignition element.

To initiate operation of the oven burner, when the mechanism is used independently of a time control, it is only necessary to manually open the main control valve, and to terminate operation it is only necessary to manually close the main control valve. The closing of the master control switch by the opening of the main control valve effects the energization of the electric ignition element which after it is energized heats the thermostatic element and causes it to flex sumciently to close one switch of the normally open pair of switches. The closing of thi switch energizes one of the solenoids which upon energization opens and holds open the normally closed valve in the branch conduit. Gas then flows to the pilot burner where it is ignited by the electric ignition element. The pilot burner then further heats the thermostatic element and causes it to flex still further. The further flexins of the thermostatic element closes the other switch of the pair of normally open switches and opens the normally closed switch which is in series with the master control switch. The closing of the other of the pair of normally open switches energizes the other solenoid which upon energization opens and holds open the normally closed valve in the main conduit. Gas then flows to the main or oven burner where it is ignited by the pilot burner. The opening of the normally closed switch de-energizes the electric ignition element which does not need to be energized after the pilot burner has been ignited. Under normal conditions the oven burner will now operate under the control of the oven temperature control valve until the supply of gas is cut ofi by the manual closing of the main control valve.

In the event the pilot burner is extinguished for any reason during operation the thermostatic element will immediately cool and return to its normal position which will open the pair of normally open switches and close the normally closed switch. The opening of the normally open switches de-energizes the two solenoids which allows the normally closed valves in the main and branch conduits to close and cut off the supply of gas to the main and pilot burners. The closing of the normally closed switch reenergizes the electric ignition element, after which both the pilot burner and main burner are re-ignited in the same manner as though the main control valve had just been turned on.

In the event of a current failure or in case the electric ignition element is rendered inoperative for any reason, the thermostatic element cannot be heated, in which case the supply of gas to both the main burner and the pilot burner will be maintained cut on by the solenoid valves in the main and branch conduits.

In order to accommodate the mechanism for use in conjunction with any standard type time control, we provide a pair of supplemental switches one of which is in series with the master control switch and the normally closed switch, and the other of which is in series with one of the normally open switches and the solenoid which controls the opening of the normally closed valve in the branch conduit. The supplemental switches are adapted to be opened and closed at predetermined set times by the time control. In use the time control is set to initiate operation of the oven burner at a predetermined set time and to terminate operation thereof at a predetermined later time, and then the main control valve is opened and the master control switch is closed. The setting of the time control opens the supplemental switch which is in series with the master switch and closes the supplemental switch which i in series with the normally open switch and the solenoid valve in the branch conduit. Then at the time set for initiating operation the time control will close the supplemental switch in series with the master control switch which will energize the electric ignition element after which the pilot burner and main burner will be ignited as previously described. At the time set for terminating operation the time control will open both of the supplemental switches which will de-energize the solenoid which has been holding the valve in the branch conduit open, and prevent re-energization of the electric ignition element until the supplemental switch in series therewith is manually closed. Both the pilot burner and the main burner will then be extinguished as previously described. Means to lock the two supplemental switches closed is provided in order that the mechanism may be used independently of the time control when desired.

A slightly modified form of the invention is shown in Figs. 4 and 5. In this form of the invention the normally closed switch which is in series with the master control switch and the electric ignition element is arranged to be opened and closed by one of the solenoids simultaneously with the opening and closing of the solenoid valve in the main conduit, instead of being opened and closed by the thermostatic element. Otherwise this form of the invention is identical with the form shown in Figs. 1 to 3 and operates in the same manner.

Another embodiment of the invention, which is not adapted for use in conjunction with a time control, is shown in Figs. 6 and '7. In this form of the invention the solenoid valve in the branch conduit through which gas is supplied to the pilot burner has been eliminated. The thermostatically operated switch which controls the operation of this valve has also been eliminated. Otherwise the structure minus the time control is the same as the form shown in Figs. 1 to 3. Immediately upon the opening of the main control valve and the simultaneous closing of the master control switch gas is supplied to the pilot burner where it is ignited by the electric ignition element. The pilot burner then heats the thermostatic element which causes it to flex and close the normally open switch and open the normally closed switch. The closing of the normally open switch energizes the solenoid which upon energization opens the normally closed valve in the main conduit after which gas flows to the main burner and is ignited by the pilot burner. The opening of the normally closed switch deenergizes the electric ignition which is not needed after the pilot burner has been ignited. If the pilot burner should be extinguished for any reason during operation the thermostatic element will immediately cool and open the normally open switch which effects the closing of the solenoid valve in the main conduit and cuts off the supply of gas to the main burner. Under this condition unburned gas can escape from the pilot burner into the oven. But the amount of gas which can escape from the pilot burner alone is so small that it is quickly dissipated and cannot collect in a sufficient quantity to do any serious damage.

The principal object of the invention is to provide an improved automatic control mechanism for cooking range oven burners using gaseous fuel.

Another object of the invention is to provide in an electric ignition and control mechanism of the character described improved means for automatically cutting off the supply of gas to both the main burner and the pilot burners in the event the pilot burner becomes extinguished for any reason before the supply of gas to both the main burner and the pilot burner has been manually cut off by the closing of the main control valve.

Another object of the invention is to provide in an electric ignition and control, mechanism automatic means for completely shutting off the supply of gas to both the main burner and the pilot burner in the event of a current failure during operation.

Another object of the invention is to provide an automatic electric ignition and control mechanism in which the supply of gas is controlled by the energization of the electrical resistance ignition element.

Other and more limited objects of the invention will be apparentfrom the following specification and the accompanying drawings forming a part thereof in which:

Fig. 1 is a diagrammatic layout illustrating one embodiment of our invention;

Fig. 2 is a plan view of the control unit showing the thermostatic element and the various switches in the positions they assume during operation of the oven burner;

Fig. 3 is a Wiring diagram of the mechanism as shown in Fig. 1;

Fig. 4 is a view similar to Fig. 1 showing a slightly modified form of the invention as shown in Fig. 1;

Fig. 5 is a wiring diagram of the mechanism as shown in Fig. 4;

Fig. 6 is a diagrammatic layout illustrating another embodiment of our invention; and

Fig. 7 is a wiring diagram of the mechanism shown in Fig. 6.

Referring now to Figs. 1 to 3 of the drawings by reference characters, the numeral 1 indicates a aseous fuel burner which is suitably mounted in a cooking range oven 2, one wall of which is shown at 3. Gaseous fuel is supplied to the burner I from a range manifold 4 through a main conduit 5. Interposed in the conduit 5 between the manifold 4 and the main burner l is a main control valve 6, an oven temperature control valve 1 and a safety control valve 8. The main control valve 6 is a cut-oil valve of standard construction which when in open or on position permits the flow of gas from the manifold 4 into the conduit 5, and in closed or off position cuts oif the flow of gas into the conduit 5 from the manifold 4. This valve is manually opened and closed by a handle 9 and valve stem I0, and directly controls the operation of the oven or main burner l since the burner cannot function unless this valve is turned on. From the main control valve 6 the gas flows to the oven temperature control valve 1 which is operative to regulate the amount of gas flowing to the burner I in order to maintain the oven at any desired set temperature. The valve 1 is set to the desired tempera ture by a handle Ii having a pointer l2 which cooperates with a graduated dial l3 carried by the valve I. The valve I is controlled according to the temperature setting by a thermostatic element l 4 which is mounted in the oven 2 and connected to the valve 1 as indicated at [5. The oven temperature control valve 1 is of standard Well known construction. Consequently it is not shown or described in detail herein. There are many different makes available, ant one of which. will work equally well herein. From. the oven temperature control valve 1 the gas flows through the safety controlvalve 8 to the burner l. The safetycontrol valve 8 is a solenoid valve of standard construction. It is biased to closed position and. is adapted to be opened and held open by a solenoid, i6, operatively connected thereto, when. the solenoid is energized. Gas is also supplied to a pilot burner ll through a branch conduit 18 which is connected to the main conduit 5 between the main control valve 6 and the oven temperature control valve 1. A solenoid valve l9 similar to but much smaller than the valve 8 is interposed in the branch conduit l8 between the main conduit 5 and the pilot burner H. The valve I9 is also biased to closed position and is adapted to be opened and. held open. by the solenoid 20, operatively connected thereto, when the solenoid. is energized.

A master control switch 22 is associated with the main control valve 8, and is adapted to be closed and opened simultaneously with the opening and closing of the main control valve 6. As the main control valve 6 is turned from the oil or closed position to the on or open position, the master switch 22 is moved from the open position to the closed position by an operating lever 23 which cooperates with a cam section 24 on the valve stem l8. Conversely, when the main control valve 6 is turned from the on or open position to the off or closed position the switch 22 is moved from the closed position to the open position.

After the main control valve 6 has been opened and the master control switch 22 has been closed the operation of the main burner i is automatically controlled by a control unit generally indicated by the numeral 25. The control unit 25 is responsive to the pilot burner l1 and comprises a thermostatic element 26, a pair of normally open switches 21 and 28, a normally closed switch 29 and an electrical resistance ignition element 30, all of which are suitably mounted upon a base 3! which is rigidly secured to the wall 3 within the oven 2. The thermostatic element 2B is the same as that shown in our copending application, Serial No. 102,534, filed July 1, 1949, and comprises an elongated flat monornetallic strip which has one end thereof rigidly secured to an upturned. flange on the base 3! as indicated at 32. The strip is slotted adjacent the anchored end thereof as indicated at 33 to provide two spaced parallel links 34 and 35 which connect the free end of the strip to the anchored end thereof. The switch 21 comprises a stationary contact 35 carried by an insulating block 3'! secured to the base 3i, and a movable contact 33 secured. to the free end of a spring arm 39, the other end of which is secured to an insulating block 4!) extending up from the base 3!. The switch 28 comprises a stationary contact 4| secured to one side of an insulating block 42 carried by the base 3! and a movable contact 43 secured to the free end of a spring arm 44 the other end of which is secured to one side of an insulating block 45 on the base 3|. The switch 29 comprises a stationary contact 46 secured to the other side of the block 42, and a movable contact 4! carried by the free end of a spring arm 48 the other end of which is secured to the opposite side of the block 45. A bar 49 of insulating material which is slidably mounted in a bore 50 in the block 42 extends between the spring arms 44 and'48 so that movement of one spring arm is imparted to the other arm. A

block of insulating material 53 is secured to the free end 54 of the thermostatic element 26 between the spring arms 39 and 44. The electrical resistance ignition element 38 is mounted directly below the link 34 of the thermostatic element 26 between a pair of spaced terminal posts which are carried by an insulating block 52 on the base 3|. The pilot burner I! is secured to the base 3|, as indicated at 55, adjacent both the electric ignition element 30 and the link 34 of the thermostatic element 26. The electric ignition element 30 is adapted when energized to heat the link 34 and to ignite the pilot burner I1; and the pilot burner H when ignited is adapted to further heat the link 34 and ignite the main burner I.

Referring now to Fig. 3, the master control switch 22 is shown as comprising two contacts 56 and 51 which are adapted to be bridged by a conductor bar 58; and a pair of supplemental switches 58 and 66 are shown as operatively associated with a standard time control mechanism 5!. The switch 59 comprises the contacts 62 and 63 and the movable conductor bar 64; and the switch 66 comprises the contacts 65 and 66 and the movable conductor bar 6?. When the time control mechanism is used the switches 59 and 60 are -adapted to be opened and closed at predetermined set times by the time control mechanism. The closing of the two switches by the time control mechanism initiates operation of the oven burner I and the opening of the two switches terminates operation thereof. When the time control is not used the switches 59 and 60 are adapted to be locked in closed position by an actuator 68.

The operation of the mechanism as used independently of the time control will now be described, reference being had to Fig. 3. To initiate the operation of the burner I the main control valve 6 is manually opened and the master control switch 22 closed. Gas will then flow from the manifold 4 as far as the normally closed solenoid valves 8 and I9. When the master control switch 22 is closed current will flow from one side ill of the line to the contact 55 of the switch 22 through the leads II and 12, and through the bar 58 to the contact 51. From the contact 51 the current will flow through the lead I3 to the contact 62 of the switch 59, and

through the bar 54 to the contact 63. From the contact 63 the current will flow through the lead I4, electric ignition element 30, lead I5, spring arm 48, contacts 41 and 46 and lead it back to the other side H of the line, thus completing the circuit through and energizing the electric ignition element 30. The electric ignition element 39 will then heat the link 34 which flexes the thermostatic element 26 just suificiently for it to close the normally open switch 21. Current will then flow from the side 70 of the line through the leads II and 18, contacts 33 and 36, lead I9, solenoid winding 20, lead 80, switch 60 and leads 8| and 16 back to the other side 11 of the line, thus energizing the solenoid 26 which when energized opens and holds open the normally closed valve IS in the branch conduit l8. Gas will then fiow through the branch conduit I8 to the pilot burner I I where it is ignited by the electric ignition element 39. After the pilot burner IT has been ignited it will further heat the link 34 which will further flex the thermostatic element 26 and close the normally open switch 28 and simultaneously open the normally closed switch 29. The

parts are now in the position shown in Fig. 2 where they will remain under the control of the pilot burner I'I, during normal operation, until operation is terminated by the manual closing of the main control valve 6 and the opening of the master control switch 22. The opening of the normally closed valve 29 breaks the circuit through and de-energizes the electric ignition element 36 which need not remain energized after the pilot burner I! has been ignited. After the normally open switch 28 has been closed current will flow from the side 19 of the line through lead I I, contacts 43 and 4 lead 82, solenoid winding I6, and leads 83 and I6 back to the other side 1! of the line, thus completing a circuit through and energizing the solenoid I6. The solenoid I6 after it has been energized will open and hold open the normally closed valve 8 in the main conduit 3. Gas will now flow to the main burner I where it is ignited by the pilot burner I l. The burner I is now in operation, and under normal conditions will continue to operate under the control of the oven temperature control valve I until the supply of gas is cut off by the manual closing of the main control valve 6.

If during operation the main burner I should be extinguished for any reason and the pilot burner I? remain ignited the main burner I will be re-ignited by the pilot burner when gas is supplied to the main burner. If the pilot burner 11 should be extinguished for any reason during operation the thermostatic element 26 will immediately cool and re-set the switches 21, 28 and 29 in the position shown in Fig. 1. This will de-energize the solenoids I6 and 20 and close the valves 8 and I9, thus shutting off the supply of gas to both the main burner I and the pilot burner IT. The closing of the switch 29 as the thermostatic element 26 cools, will re-energize the electric ignition element 30 after which both the pilot burner I1 and the main burner I will be reignited as just described.

If it is desired to use the time control SI, it is first set to initiate operation at a predetermined time and to terminate operation at a predetermined later time and then the main control valve 6 is opened and the master control switch 22 is closed. The setting of the time control 6| opens the switch 59 and closes the switch 66. At the set time for initiating operation the time control will close the switch 59, completing the circuit through and energizing the electric ignition element 30. After the ignition element 30 has been energized the pilot and main burner will be ignited and operate as previously described. At the set time for terminating operation the time control will open both the switch 59 and the switch 60. The opening of the switch 60 breaks the circuit through and de-energizes the solenoid 20 which closes the valve I9 and cuts ofi the supply of gas to and extinguishes the pilot burner I1. The thermostatic element 26 then cools and opens the switch 23 which breaks the circuit to and de-energizes the solenoid I6 and closes the valve 8, cutting on the supply of gas to the main burner. The main control valve 6 may then be closed and the master switch opened at any time.

Figs. 4 and 5 shows a slight modification of the mechanisms shown in Figs. 1 to 3. In this form of the invention the-normally closed switch 29 has been removed from the control unit 25 and arranged to be opened and closed by the solenoid If; as it opens and closes the valve 8. Otherwise this form of the invention is identical in 9 oonstruction and operation with that shown in Figs. 1 to 3. The same reierencecharacters have been applied to like parts in the two forms and the description of the construction and operation of Figs. 1 to 3 also applies to Figs. 4 and 5.

Figs. 6 and 7 show another modification of the mechanism shown in Figs. 1 to 3. In this form of the invention the normally closed valve IS in the branch conduit is, the solenoid 2H and the switch 21 which controls the energization of the solenoid 26, have been eliminated. This form of the invention is not adapted for use in conjunction with a time control mechanism. Otherwise this form is identical in construction with that shown in Figs. 1 to 3. The same reference characters have been applied to like parts in the two forms and the description of the construction of Figs. 1 to 3 also applies to Figs. 6 and '2. When the main control valve 6 is opened and the master switch 22 has been closed gas is immediatelysupplied to the pilot burner I i which is ignited by the electric ignition element 35. The pilot burner then heats the thermostatic element 2% which then closes the switch 23' and opens the switch 29. The opening of the switch 29 breaks the circuit to and de-energizes the electric ignition element 38; and the closing of the switch 23 energizes the solenoid l6 which opens the normally closed valve 8 after which gets flows to the main burner I which is then ignited by the pilot burner l1.

From the foregoing it will be apparent to those skilled in this art that we have provided a very simple, practical and efficient mechanism for accomplishing the objects of the invention. v

It is to be understood that we are not limited to the specific construction shown and described herein as various modifications may be made therein withinthe spirit of the invention.

What is claimed is: a

1. In an apparatus of the character described, the combination of a gaseous fuel burner, a main condu-it through which gaseous fuel is supplied to said burner, a manually operable main control valve interposed in said conduit, a normally closed" safety control valve interposed in said conduit between said main control valve and said burner, a solenoid operative when energized to maintain said normally closed safety control valve open, a pilot burner operative when ignited to ignite said burner, a branch conduit through which gaseous fuel is supplied to said pilot burner from said main conduit intersecting said main conduit between said maincontrol valve and said safety control valve, an electric ignition element operative when energized to ignite said pilot burner, a manually operable master control switch, a normally open switch in series with said solenoid, a normally closed switch in series with said master control switch and said electric ignition element, and a thermostatic element mounted in position tobe heated first by said electric ignition element and then further heated by said pilot burner, said thermostatic element being operative when heated to maintain said normally open switch closed and said normally closed switch open.

2'. In an apparatus of the character described, the combination of a gaseous fuel burner, a main conduit through which gaseous fuel is supplied to said burner, a manually operable main control valve interposed in said conduit, a normally closed safety control valve'interposed' in said conduit between said main control valve and said burner, a solenoid operative when energized to maintain'said normally closed safety controlvalv'e' It open, a pilot burner operative when ignited to ignite said burner, a branch conduit through which gaseous fuel is supplied to said pilot burner from said main conduit intersecting said main conduit between said main control valve and said safety control valve, a normally closed valve interposed in said branch conduit between said main conduit and said pilot burner, a second solenoid operative wheneiiergized to maintain said normally closed valve open; an electric ignition element operative when energized to ignite said pilot burner, a manually operable master control switch, a pair oi nor mally open switches one of said switches being series with said solenoid and the other of saidswitches being in series with said second solenoid, a normally closed switch in series with said master control switch andsaid electric ignition element, and a thermostatic element Inountefdp'osition to be heated first by said electric ignition element and then further heated by said pilot burner, said thermostatic element being operative when heated to maintain said p'aijr of normally open switches closed and said normally closed switch open.

3. In anapparatusof the character described, the combination of agaseous fuel burner, a main conduit through w chgaseous fuel is supplied to said burner, a manually operable main control valve interposed'in saidconduit, a normally closed safety comics valve interposed in said conduit between said main control valve and said burner, a solenoid operativewhen energized to maintain said normally closed saiety control valve open, a pilot burner operative when ignited to ignite said burner, a branch condui through which gaseous fuel is supp led-to sa d pilot burner from said mainconduit intersecting said main conduit between 5 mainco'ntrolvalve and said safety controlvalv anormally closed valve interposed in said branch conduitbetween said main conduit and: said pilot burner, a second solenoid operative when energized to mai saidnormally closed valve open, an electric ign 1on element operative when energized to ignitesaid pilot burner, a manually' operable master 'trol switch, a normally openswitch inseries with said second solenoid, a seeond no'r aliyope'n switch in series with said solenoid, anormally closed switch in series with said master" control switch and said electric ignition element; and a thermostatic element mounted positionto be heated first by said electric ignition element and then further heated by said pilot burner anaemia-ave when heated to successively close said normally open switch and second normallyopen' switch and to open said ndffllallYclbsd S hub.

45; apparatus of the character described, the combination ofa: gaseous fuel burner, a main conduit tli ugh gaseous fuel is supplied to turner, a r'l ianuall'y operable main control valve interposed in said conduit, a normally closed safetycontrbl valve interposed'in said condui t between saidn'iaiir control valve and said burner; a solenoid operative when energized to maihtaifisa-id noi ln yclosed safety control valve open, a pilot bu ner operative when ignited to ignite" said burner; a branch conduit through which gaseous fuel is supplied to said pilot burner from Said main conduit intersecting said main conduit between saidmairicontrol valve and said sai etycontrel"valvaamorinallyclosed valve interposedsa-id branch conduit between said main conduitand said pilot burner, a second solenoid operative when energized to maintain said normally closedvalveopefi, an electric ignition element operative when energized to ignite said pilot burner, a manually operable master control switch, a normally open switch in series with said second solenoid, a second normally open switch in series with said solenoid, a normally closed switch in series with said master control switch and said electric ignition element, and a thermostatic element adapted to be first heated by said electric ignition element and then further heated by said pilot burner, said thermostatic element being operative when heated by said electric ignition element to close said normally open switch and when further heated by said pilot burner to close said second normally open switch and to open said normally closed switch.

5. In an apparatus of the character described, the combination of a gaseous fuel burner, a main conduit through which gaseous fuel is supplied to said burner, a manually operable main control valve interposed in said conduit, a normally closed safety control valve interposed in said conduit between said main control valve and said burner, a solenoid operative when energized to maintain said normally closed safety control valve open, a pilot burner operative when ignited to ignite said burner, a branch conduit through which gaseous fuel is supplied to said pilot burner from said main conduit intersecting said main conduit between said main control valve and said safety control valve, a normally closed valve interposed in said branch conduit between said main conduit and said pilot burner, a second solenoid operative when energized to maintain said normally closed valve open, an electric ignition element operative when energized to lgnite said pilot burner, a manually operable master control switch, a normally open switch in series with said second solenoid, a second normally open switch in series with said solenoid, a normally closed switch in series with said master control switch and said electric ignition element, and a thermostatic element adapted to be first heated by said electric ignition element and then further heated by said pilot burner, said thermostatic element being operative when heated by said electric ignition element to close said normally open switch and when further heated by said pilot burner to close said second normally open switch, and means responsive to the opening and closing of said safety control valve operative to open said normally closed switch upon the opening of said safety control valve and to close said normally closed switch upon the closing of said safety control valve.

5. An apparatus as defined in claim 2 having a clock-actuated switch in series with said electric ignition element, a second clock-actuated switch in series with said second solenoid, and a clock mechanism operative to actuate said clock-actuated switches at predetermined set times.

7. An apparatus as defined in claim 4 having a clock-actuated switch in series with said electric ignition element, a second clock-actuated switch in series with said second solenoid, and a clock mechanism operative to actuate said clock-actuated switches at predetermined set times.

8. An apparatus as defined in claim 5 having a clock-actuated switch in series with said electric ignition element, a second clock-actuated switch in series with said second solenoid, and a clock mechanism operative to actuate said clockactuated switches at predetermined set times.

9. A control unit for a cooking range oven burner using gaseous fuel comprising a base, a thermostatic element mounted on said base, an electric ignition element mounted on said base in position to heat said thermostatic element, a pilot burner mounted in position to be ignited by said electric ignition element and to project a flame against said thermostatic element and further heat said thermostatic element, a normally open first switch mounted on said base, a second normally open switch mounted on said base, and a normally closed switch mounted on said base, said thermostatic element being operative when heated by said electric ignition element to close said first normally open switch and when further heated by said pilot burner to close said second normally open switch and open said normally closed switch.

10. A control unit for a cooking range oven burner using gaseous fuel comprising a base, a thermostatic element mounted on said base, an electric ignition element mounted on said base in position to heat said thermostatic element, a pilot burner mounted in position to be ignited by said electric ignition element and to project a flame against said thermostatic element and further heat said thermostatic element, a normally open first switch mounted on said base, a second normally open switch mounted on said base and a normally closed switch mounted on said base, interconnecting means between said second normally open switch and said normally closed switch through which said second normally open switch and said normally closed switch are actuated in unison, said thermostatic element being operative when heated by said electric ignition element to close said first normally open switch and when further heated by said pilot burner to simultaneously close said second normally open switch and open said normally closed switch.

11. A control unit for a cooking range oven burner using gaseous fuel comprising a base, a thermostatic element mounted on said base, an electric ignition element mounted on said base in position to heat said thermostatic element, a pilot burner mounted in position to be ignited by said electric ignition element and to project a flame against said thermostatic element and further heat said thermostatic element, a nor mally open first switch mounted on said base, a second normally open switch mounted on said base, said thermostatic element being operative when heated by said electric ignition element to close said first normally open switch and when further heated by said pilot burner to close said second normally open switch.

12. A control unit for a cooking range oven burner using gaseous fuel comprising a base, a thermostatic element mounted on said base, an electric ignition element mounted on said base in position to heat said thermostatic element, a pilot burner mounted in position to be ignited by said electric ignition element and to project a flame against said thermostatic element and further heat said thermostatic element, a normally open switch mounted on said base, and a normally closed switch mounted on said base, said thermostatic element being operative when heated by said electric ignition element to close said normally open switch and when further heated by said pilot burner to open said normally closed switch.

13. A control unit for a cooking range oven burner using gaseous fuel comprising a base, a thermostatic element mounted on said base, an

electric ignition element mounted on said base' 13 14 in position to heat said thermostatic element, a pilot burner mounted in position to be ignited by References Cited in the file Of this Patent said electric ignition element and to project a UNITED STATES PATENTS flame against said thermostatic element and further heat said thermostatic element, a plurality 5 Number N Date of switches mounted on said base, said thermo- 2207297 Wllhams 1937 static element being operative when heated by 2221'667 Betz, 1940 said electric ignition element to actuate one of 552 2 -?g said switches and when further heated by said 2,395,666 Kaufmann Feb 26 1946 pilot burner to actuate others of said switches. 10

CHARLES M. MAYER. SAMUEL T. CRAIG. 

